INSIGHTS OF THE EFFECTS OF POLYETHYLENE GLYCOL 400 ON MAMMALIAN AND AVIAN NERVE TERMINALS

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Polyethylene glycol (PEG) has been widely used as a solvent among other applications. An ideal solvent is one that does not interfere with an in vitro biological system, unless it is a bioactive agent. Herein, a facilitatory neurotransmission effect was exhibited by PEG (20 mu M) in mammalian (67 +/- 12.5%, n = 4) and avian (74 +/- 6.8%, n = 6) neuromuscular preparations. In curarized preparations, PEG did not reverse the neurotransmission blockade induced by D-tubocurarine (D-Tc, 5.8 mu M, n = 6) as promoted by neostigmine (12 mu M, n = 4). A possible presynaptic action of PEG was ruled out, because quantal acetylcholine (ACh) content was similar to the control Tyrode-incubated mammalian preparation. PEG showed improved sarcolemmal sensitivity, both under direct (sarcolemma) and indirect stimulation (motor axon), because it was able to release calcium from the sarcoplasmic reticulum, even when 30 pM dantrolene (n = 5) was previously applied. Neurotransmission decreased at a higher PEG concentration (100 mu M, n = 6) in the depolarized membrane, but it did not alter normal muscle fiber morphology. In addition, it partially recovered twitch tension amplitude (55 +/- 5.7%) after washing the preparations. More than a simple solvent, we suggest that PEG 400 is able to act on the sarcolemmal membrane, probably at the triad level, which is in line with its well-known ability as drug carrier Muscle Nerve 41: 540-546, 2010414540546Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)FAEPFX/UNICAMPFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES